The saga of Middle-earth continues. Houghton Mifflin Harcourt announced Wednesday that it will publish “The Fall of Gondolin,” an unpublished story by J.R.R. Tolkien, on Aug. 30. The book will sell for $30.

Tolkien, the author of “The Hobbit” and “The Lord of the Rings,” died in 1973 but left behind unpublished manuscripts that have been edited by his son Christopher Tolkien. The new book follows the success of two earlier volumes, “The Children of Húrin” (2007) and “Beren and Lúthien” (2017), which continued the author’s depictions of the fantasy realm of Middle-earth.

“The Fall of Gondolin” will feature illustrations by Alan Lee, who contributed to earlier Tolkien volumes and won an Academy Award in 2004 for his work on “The Lord of the Rings: The Return of the King,” the third of Peter Jackson’s successful film adaptations.